Saliva is the most relevant biological factor for the prevention of dental erosion. It starts acting even before the acid attack, with an increase of the salivary flow rate as a response to the acidic stimuli. This creates a more favorable scenario, improving the buffering system of saliva and effectively diluting and clearing acids that come in contact with dental surfaces during the erosive challenge. Saliva plays a role in the formation of the acquired dental pellicle, a perm-selective membrane that prevents the contact of the acid with the tooth surfaces. Due to its mineral content, saliva can prevent demineralization as well as enhance remineralization. These protective properties may become more evident in hyposalivatory patients. Finally, saliva may also represent the biological expression of an individual's risk for developing erosive lesions; therefore, some of the saliva components as well as of the acquired dental pellicle can serve as potential biomarkers for dental erosion.